This generic name was originally applied by Schimper[735] to certain forms of Calamitean stems, of the type afterwards referred to the sub-genus _Calamitina_ by Weiss, bearing long and thick cones. The name is, however, more appropriately restricted to strobili, which differ from the two preceding genera in their greater length (14–16 cm.) and in the more crowded and imbricating whorls of bracts. The internodes of the cones are very short, and each whorl of bracts consists of about 20 coherent members separated at the periphery of the disc into short pointed teeth. The internal structure of _Macrostachya_ has not been satisfactorily determined. An account by Renault[736] of a petrified specimen does not present a very clear idea as to the structural features of this form of Calamitean strobilus. THE ASSOCIATION OF CALAMITEAN VEGETATIVE SHOOTS AND CONES. Strobilus | Foliage-shoot | Stem ------------------------+----------------------+------------------------- _Calamostachys_ | _Annularia ramosa_ | _Calamites ramosus_ (_Stachannularia_) | Weiss | Artis _ramosa_ Weiss[737] | | | | _C._ (_Stachannularia_) | _A. sphenophylloides_| Stem bearing verticils of _calathifera_ | Zenk. | long and narrow Weiss[738] | | leaves[739]. Probably a | | young _Calamites_ | | _C._ (_Stachannularia_) | _A. stellata_ | _tuberculata_ (Stern.)| (Schloth.)[740] | _Calamites_ sp.[741] |(_A. longifolia_ | | Brongn.) | | | _C. Solmsi_[742] Weiss | _Calamocladus_ sp. | _Calamites_ (_Calamitina_) | | sp. | | _C. longifolia_ | _Calamocladus_ sp. | (Stern.)[743] | | | | _Palaeostachya_ | _Calamocladus_ | _pedunculata_ | | Will.[744] | | | | _P. arborescens_ | | _Calamites_ (Stern.)[745] | | (_Stylocalamites_) | | _arborescens_ (Stern.) | | _Macrostachya_[746] | _Calamocladus_ | _Calamites_ (_Calamitina_) | _equisetiformis_ | sp. | (Schloth.) | [Sidenote: HUTTONIA.]